An on-demand service system can arrange for an on-demand service to be provided for a requesting user by a service provider. In some examples, the service provider's automobile may be equipped with various on-board sensors. These sensors may draw power from the service provider's automobile and may communicate wirelessly with a mobile handset to relay sensor data to a server associated with the on-demand service system. The on-demand service system may use the sensor data to monitor the status, and/or location, of its service providers.